Drum series print member construction



June 27, 1967 c H. CLARK ETAL DRUM SERIES PRINT MEMBER CONSTRUCTION 5Sheets-Sheet 1 Original Filed April 5, 1962 INVENTORS CLA yrolv H- CLARK[Jo/v.4 L0 J. STEFAN/K ATTORNEYS June 27, 1967 c H. CLARK ETAL 3,327,626

DRUM SERIES PRINT MEMBER CONSTRUCTION Original Filed April 5, 1962 .5Sheets-Sheet 2 INVENTORS CLAYTON h. CLARK DONALD J. STEFAN/K BY WY/WZ/MWax/M13 ATTORNEYS June 27, 1967 c. H. CLARK ETAL DRUM SERIES PRINTMEMBER CONSTRUCTION 5 Sheets-Sheet 5 Original Filed April 5 1962 F Y M yW m w 3 N 5 5 O ,W 0 6 MM 1 w. m m m m am z W y g w 1 5 w m Wl/Wl/fi Q.2. LFII.||./ 1 n 2 w m n Y 7- B O LWHYP BM LWHYPOOB & .Ll

United States Patent Claims. (Cl. 101110) This application is a divisionof copending application Ser. No. 184,820 filed Apr. 3, 1962, Patent No.3,280,256.

This invention relates to a communications equipment drum printerprimarily intended for use in high speed telegraphic and other dataprocessing applications and particularly relates to construction of theprinter drum.

The inventive drum type of continuously rotating page printerincorporates an inexpensive yet reliable and rugged drum construction,constituting the invention of this application.

Accordingly, a primary object of this invention resides in the provisionof a novel drum printer drum construction.

A further object resides in the provision, in a continuously rotatingdrum printer, of a novel rotatable drum assembled from a plurality ofrings of. printing elements to provide lines of identical type facesextending from a start-of-line position to an end-of-line position on apage, each ring being of novel lightweight construction and maintainedin accurate indexed assembly by means of clamping end plates and thefrictional engagement between each adjacent ring, and specifically byproviding such frictional engagement at the peripheries of adjacentrings.

In conjunction with aspects of the preceding object, still anotherobject resides in providing the rings of printing elements on peripheralflanges of print wheels, each of. which wheels has identical dual rowsof all desired characters-to-be-printed on the printer and with thecenter lines of axially aligned, identical characters accurately spacedapart a predetermined distance and also accurately spaced from theadjacent edges of the peripheral flange one half of that predetermineddistance and the axial width of the wheel peripheral flange beingmaintained to extremely minute tolerances.

Still another object resides in the provision of a novel drum printerprint drum made from a laminated assembly of print wheel rings whereineach ring has a T-shaped radial cross-section with the circularperipheral portion of a ring carrying the printing symbols andconstituting the cross flange of the T-section.

Other objects and novel aspects of the drum printer and its componentswill become apparent in conjunction with the description and theappended claims.

FIGURE 1 is a front perspective view of the printer, primarily toillustrate the general arrangement of printer components and thereforeomitting many details which are illustrated in the following figures;

FIGURE 2 is a partially section elevation view showing the print drumwith its drive gear, clock assembly, and bearing mounting and alsoillustrating the paper feed components;

FIGURE 3 is a side elevation view of one of the plurality of doubletypewheel discs from which the type drum is assembled;

FIGURE 4 is a layout detail view of a portion of the double type on theperiphery of a typewheel; and

FIGURE 5 is a machine drawing detail, shown in section taken on lines5-5 of FIGURES 3 and 4, and illustrates the drum assembly register slotand the requisite manufacturing tolerances for a disc with standardteletypewriter characters.

General A perspective view of an exemplary teleprinter 102 is shown inFIGURE 1. This equipment was initially developed for high-speedtelegraphic communication in conjunction with a complete send-receivesystem designed for keyboard sending and magnetic tape recorder sending,page copy monitoring and page copy receiving. The entire system is morefully disclosed in copending parent application Ser. No. 184,820 towhich reference may be made for details of printer structure andoperation. The invention in this application pertains to the printerdrum construction and hence other details of the printer and itsspecific operation will not be described herein.

The printing mechanism, described briefly, employs a rotating drumcomposed of thirty-six double row type wheels, or a total of 72 rings oftype, each ring having the 52 standard communication symbols. Otherarrangements can be accommodated as desired. For example, for weathersymbols, the drum has 76 rings of type, each ring having 52 conventionalweather symbols. A print hammer is moved from left to right in front ofthe drum under control of an escapement type spring-biased steppingmechanism and strikes the drum once per revolution for each character tobe printed. The printing mechanism has a pulse clock mechanism whichsupplies a series of pulses to the printer electronics representative ofdrum rotational position. Since each pulse represents a new character inthe printing position, the pulses furnish information which allows theprinter electronics to energize the print hammer electro-magnet as thedesired character moves in front of the hammer. Characters on each ringof type are placed in binary order according to the Baudot code for thecharacter. Thus, each character is assigned a position in a 32-count,binary progression so that the printer electronics can compare anincoming character against the series of pulses that indicate thephysical position of the drum characters.

Printer mechanics FIGURE 1 provides an over-all picture of themechanical components of the type drum page printer 102 and thepositional relationships of various components.

In general terms, the drum 704 includes, on its cylindrical periphery, aplurality of different lines of identical information symbols, 72identical symbols (76 for a weather drum) constituting one lineextending along the cylindrical drum periphery parallel to the drumaxis. The drum is continuously rotated by a printer motor (not shown)and is directly connected with a drum position clock wheel 706 to enabledetermination of the passage of each distinct line of type past a printstation line by related printer electronics which have been described inthe aforenoted parent application. A print hammer carriage 708 can bespaced across in front of the drum surface, parallel to the drum axis,by an escapement spacing mechanism actuated by spacing solenoid 204 atthe right hand side plate. The carriage 708 is returned by a carriagereturn mechanism seen at the left hand side of FIGURE 1, which isactivated by the carriage return solenoid 308. Power for carriage returnis derived through a clutch device driven by the printer motor.

A sheet paper, strip record medium is supplied from a paper roll 712mounted between the frame end plates, to the rear of drum 704, the paperfeeding over suitable guide devices (not shown), under and up past thefront of the drum, passing between the drum 704 and the print hammercarriage 708 and under two, side edge guide fingers 713, one being shownin FIGURE 2. Paper feed is accomplished by two, solenoid stepped,pressure rolls under the drum which press the paper against two feedwheels at the ends of the print drum.

An ink ribbon 716 passes across the drum face parallel to the drumbetween the print hammer and the paper to transfer the typed impressionfrom the drum to the page during a print operation. The ink ribbonassembly feed and reverse mechanism is conventional and will not bedescribed. However, the ink ribbon 716 in this printer is rigged toalways pass in a straight stretch across the front of the drum 704parallel to the character spacing path of the print hammer, and theentire straight front stretch of the ink ribbon is lifted to a positionin front of the hammer just prior to a printing action.

As shown in FIGURE 1, the printer components are mounted on a supportstructure including a thick base plate 718 having a slotted center bar719 passing laterally from one side of the printer to the other andunder the path of travel of the print hammer carriage. Two vertical sideplates 720 and 721 are rigidly secured to the base plate 718 and providethe mounting structure for most of the printer components.

Drum assembly Referring now to FIGURE 1 (also FIGURES 3-5), the printdrum 704 is pre-assembled in an inexpensive manner as compared withpreviously known drums for type drum printers which were engraved fromsolid materials. (Cost of the fabricated type wheel drum of the presentinvention is approximately that of an engraved drum.) The drum 704 isfabricated from a plurality of double row type wheels 722, manufacturedto very close tolerances, mounted, indexed and clamped on a drum shaft723 in a manner now to be described.

As depicted in FIGURES 35, each type wheel 722 is made from a suitablehigh strength material capable of withstanding multiple print hammerblows and maintaining true circular shape under continual rotation.Steel, other presently known high strength metals and some plastics canbe used. The wheel 722 has a central, disc shaped, thin web 724apertured with lightening holes 725, an indexing hole 726 and balanceholes 727 and 728.

The rim 730 of each type wheel 722 provides a peripheral T-flangecarrying two axially spaced apart rows of raised printing symbols, suchas letters, numbers, punctuation, etc., each pair of side by side raisedsymbols being identical and disposed with their center lines extremelyaccurately equidistant from the web center plane and also accuratelyequidistant from the nearest adjacent edge of the rim 730, as shown byrepresentative actual values on FIGURE 5. The edges of rim 730 are fiatand are accurately disposed in parallel planes normal to the wheel axis.As clearly depicted in FIGURE 5, the true axial dimension of the rimT-flange 730 is 0.2000" which is the distance of space required for twostandard teletypewriting symbols, and this dimension is held to anextremely close tolerance range of $00005". This tolerance value isnecessitated to prevent a buildup of a 72 character line, space error inan assembled drum. If the center line spacing of each of the two rows ofcharacters is maintained within tolerances of :0.003 the overallcharacter space tolerance of each character relative to adjacentcharacters and of the entire line of characters will be well within theacceptable limits.

The five-unit Baudot code permits of thirty-two different code bitcombinations and, using letters and figures shift functions, sixty-fourcharacters can be realized. Accordingly, in the exemplary printer,sixty-four positions are provided around the periphery of each typewheel rim 730 and all characters are accurately located at specificangular positions. A layout portion of a wheel rim is seen in FIGURE 4.

To assure that all wheels 722 are assembled in proper indexed alignmentwith the adjacent wheel, an index slot 726 is made in the web 724 ofeach wheel, the slot center line being aligned with one and the samespecific character on all wheels. The web center holes 731 of all Websare also accurately located and are dimensioned to provide a smoothguided coaxial fit on the drum shaft 723. By means of a suitable jig,the index slots 726 are aligned before and during torqueing of the drumassembly into clamped assembly, as will be now described.

Going back to FIGURE 2, an intermediate length 733 of drum shaft 723 isdimensioned to fit the center holes 731 of the type wheels 722. Bothends of the intermediate shaft section 733 are threaded as indicated at734. A suitable number (36- or 38) of wheels 722 are placed on the shaft723, indexed to align the same characters on all wheels and clampedtogether by two end clamping plates 735, adjacent spacers 736 and nuts737, the latter being threaded and torqued very tightly on the threadedends of the intermediate shaft section 733. (Note: with 38 wheels, thespacers 736 are omitted.) The center holes 738 of clamp plates 735 arethe same size as the type wheel center holes 731 and also have a smootheoaxially locating fit on drum shaft intermediate portion 723. The outerperiphery of each clamp plate 735 is provided with a right angledannular flange 737 which faces the stack of type-wheels and fits with aslight radial clearance coaxially within the circumscribing axiallyextended end flange of the rim T-fiange 730 of the adjacent type wheel722, abutting the wheel web 724 in annular contact. This fit transfersan even annular clamping force from plates 725 to the webs of the endwheels and thence to the outer periphery of each of the end type wheelsof the assembled drum 704 and thus, the clamping pressure is evenlytransferred through the fiat abutting rim edges of all adjacenttypewheels 722. This clamping pressure is all that is required to holdall typewheels in true indexed alignment. Both sets of clamping plates735, spacers 736 and nuts 737 are locked together, after the clampingpressure is achieved, by a roll pin 740.

A left hand bearing retainer assembly 742, which carries a bearing 743in a socket 744, is placed over the left hand reduced diameter end 745of the drum shaft 723 with the inner race of the bearing 743 against ashoulder 746 formed between the shaft end 745 and the shaft intermediatesection 733. A somewhat. similar right hand bearing retainer assembly747 and shaft bearing are placed over a right hand reduced end portion776 of the drum shaft 723. Right hand bearing assembly 747, as shown inFIGURE 2, includes an integral clock head mounting plate 748, whichserves to rigidly mount the printer clock monitor heads 180, 184 and186, etc.

Before the hubs 749 and 750 of respective bearing retainers 742 and 747are clamped in sockets on respective printer frame end plates 720 and721 by clamping blocks 751 and 752, left and right hand record mediumfeed wheels 753 and 754, with associated ring gears 755 and 756, areplaced on external bushing sleeves 757 and 758 integral with theassociated bearing retainers. The feed wheel gears 755, 756, are clampedto the respective feed wheels 753 and 754 by screws and split, annularring clamping plates 759 which fit into and ride in grooves 760 in thebearing retainer body to axially maintatin the feed wheels 7523 and 754in position adjacent each end of the drum 704.

. A rubber O-ring 761 is stretched over the periphery of each feed wheel753, 754 and fitted into half circle grooves 762 in the periphery of itsfeed wheel, and then cut or ground down almost even with the feed wheelperiphery to serve as a friction band to engage and line feed the pagerecord medium, by means to be hereinafter described. If desired, theO-ring 761 may be cemented in the groove 762 but it is not necessary.Note, the feed wheels are now rotatably mounted on the bearing retainerswhich will be clamped in adjacent printer frame end plates 720 and 721and the drum 704 is rotatably mounted relative to the bearing retainers,completely independent of the record feed wheels 753 and 754.

Drum drive.Assembled in the frame, as seen in FIG- URE 2, the left handdrum shaft end 745 projects beyond the bearing retainer 742 and a gear770 is non-rotatably secured thereto by set screws 771. The printermotor (not shown) is mounted on the inside of frame plate 720 with itsshaft 772 projected through the plate and carrying a drive gear 773. Agear tooth drive belt 774 meshes with motor gear 773, drum gear 770 anda carriage return clutch input gear and when the printer motor isenergized the drum 704 will continually rotate.

The clock wheel 706 is non-rotatably secured to the right hand drumshaft end 776, and has peripheral reference notches 777 properly locatedrelative to the angular positions of the print characters on the drum704.

The clock wheel 706 rotates with the print drum 704 and as it rotates,the moving notches vary the reluctance of bar type magnets located inthe clock monitor head coils 180-186 inducing appropriate current pulsesinto associated transistor amplifiers, as described in the aforenotedparent application.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come Within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. In a data processing drum printer:

a frabricated multiple character print drum having lines of raised typesymbols across its cylindrical perphery, said drum being fabricated froma plurality of coaxial typewheels, each typewheel comprising:

an outer peripheral, axially flanged, circular rim,

and

a thin intermediate web portion integral with and circumscribed by saidrim; said outer peripheral rims of adjacent typewheels axially abuttingeach other and means clamping all typewheels together in coaxialrelationship and maintaining them in coaxial and predetermined angularposition relative to each other; said clamping means exerting an axiallydirected pressure on the plurality of typewheels causing an axiallydirected pressed abutment between the peripheral rims of adjacenttypewheels.

2. A print drum as defined in claim 1, wherein said web portion of everytypewheel includes means accurately located relative to a specificpredetermined angular location of said raised type symbols enablingaccurate angular assembly of said plurality of typewheels.

3. A data processing drum printer print drum as defined in claim 1wherein each one of said lines of raised type symbols has similar typesymbols.

4. A data processing drum printer comprising:

a fabricated multiple character print drum having lines of similarraised type symbols across its cylindrical periphery parallel to thedrum axis, said drum being fabricated from a plurality of typewheels,each typewheel having:

a flanged outer peripheral annular rim having a T-shape in radial crosssection, and a thin coaxial locator Web portion;

the outer rims of adjacent typewheels axially abutting each other;

means coaxially clamping all typewheels together and maintaining them inindexed position by exerting axial clamping pressure through saidtypewheel peripheral flanges; and

the width of the rim flange on each typewheel being made to equaldimensions in all typewheels, held to a close manufacturing tolerance onthe order of +0.0005 inch.

5. In the print drum as defined in claim 4, each typewheel web portionbeing centrally apertured to provide a coaxial locator and having aneccentric aperture with edge means accurately located relative to saidtype symbols to enable accurate angular assembly of said plurality oftypewheels.

6. A drum printer print drum having an axis and com prising: a pluralityof individual rings, each ring being a print wheel having an innerradial disc-like web with an outer periphery and having printing symbolelements located around said outer periphery, said rings assembled as alaminated drum with at least the major extent of said radial webs ofadjacent ones of said rings being spaced apart; said rings havingabutment portions extending axially from said webs and disposed closerto said outer peripheries than to said drum axis with said abutmentportions on adjacent ones of said rings being in pressed engagement witheach other; and clamping means engaging and exerting opposed force onthe ones of said rings constituting the end rings in said drum therebytransmitting axially directed pressure through said rings at saidabutment portions to facilitate maintenance of said rings in apredetermined position relative to each other with lines of saidprinting symbol elements extending across the outer peripheral surfaceof said laminated drum.

7. A drum printer print drum as defined in claim 6, wherein saidclamping means comprise clamping end plates, one of which is located ateach end of said plurality of rings.

8. A drum printer print drum as defined in claim 7, wherein saidclamping end plates engage and apply clamping pressure adjacent theouter periphery of each end ring.

9. A drum printer print drum as defined in claim 6, wherein saidprinting symbol elements are raised type symbols.

10. A drum printer print drum as defined in claim 6, wherein each ringis made from lightweight material and includes a plurality of lighteningholes.

11. A drum printer print drum as defined in claim 6, where each ring hasa T-shaped radial cross-section with the circular peripheral portioncarrying the printing symbol elements constituting the cross flange ofthe T-shaped section.

12. A drum printer print drum as defined in claim 11, wherein saidprinting symbol elements are raised type symbols.

13. A drum printer print drum as defined in claim 11, wherein saidflanges constitute said abutment portions, each of said rings hasidentical dual rows of all desired character symbols to be printed bythe printer, the center lines of axially aligned identical characters insaid dual rows are accurately spaced apart a predetermined distance andare also closely accurately spaced from the adjacent edges of theperipheral flange one-half of that predetermined distance, and

the axial widths of said peripheral flanges of all of said rings aremaintained to the same dimension with an extremely minute tolerance.

14. In a data processing drum printer: a multiple character print drum,said drum being assembled from a plurality of coaxial typewheels, eachtypewheel including a radially extending web having a center hole,raised type symbols at the periphery of said web, and axially extendingflange means integral with said web and spaced radially outward asubstantial distance from said center hole, said flange means ofadjacent typewheels being in pressed abutment with each other, andclamping means transmitting axially directed clamping pressure throughsaid flange means causing axially directed pressure abutment betweenadjacent typewheels for facilitating maintenance of said typewheels inpredetermined alignment relative to each other.

15. A drum printer print drum as defined in claim 14, wherein the soleplace of contact between adjacent typewheels is at said flange means.

References Cited UNITED STATES PATENTS 12/1905 De Coppet 101-1 10 8/1909Wilhelm 101--'11O 6/1934 Cook 101-375 2/1936 Bennett 101-110 X 3/1952Dudis 101109 11/1959 Christofi et .al. 101-93 8/1962 Brown et a1. 10193FOREIGN PATENTS 4/ 1933 Germany.

15 WILLIAM B. PENN, Primary Examiner.

1. IN A DATA PROCESSING DRUM PRINTER: A FABRICATED MULTIPLE CHARACTERPRINT DRUM HAVING LINES OF RAISED TYPE SYMBOLS ACROSS ITS CYLINDRICALPERIPHERY, SAID DRUM BEING FABRICATED FROM A PLURALITY OF COAXIALTYPEWHEELS, EACH TYPEWHEEL COMPRISING: AN OUTER PERIPHERAL, AXIALLYFLANGED, CIRCULAR RIM, AND A THIN INTERMEDIATE WEB PORTION INTEGRAL WITHAND CIRCUMSCRIBED BY SAID RIM; SAID OUTER PERIPHERAL RIMS OF ADJACENTTYPEWHEELS AXIALLY ABUTTING EACH OTHER AND MEANS CLAMPING ALL TYPEWHEELSTOGETHER IN COAXIAL RELATIONSHIP AND MAINTAINING THEM IN COAXIAL ANDPREDETERMINED ANGULAR POSITION RELATIVE TO EACH OTHER; SAID CLAMPINGMEANS EXERTING AN AXIALLY DIRECTED PRESSURE ON THE PLURALITY OFTYPEWHEELS CAUSING AN AXIALLY DIRECTED PRESSED ABUTMENT BETWEEN THEPERIPHERAL RIMS OF ADJACENT TYPEWHEELS.